Amine-containing materials, such as amine-containing analytes, amino acids, DNA fragments, RNA fragments, protein fragments, organelles, and immunoglobins, immobilized on the surface of a substrate can be used in numerous applications. The covalent attachment of amine-containing materials to a substrate can be accomplished, for example, by the reaction of the amine with a reactive group on the surface of the substrate. This amine-reactive functional group can be, for example, an activated acyl derivative, such as an N-hydroxy succinimide ester; or, an active cyclic acyl compound, such as azlactone. A stable amide bond is formed from reaction of the amine with the active acyl group, either with expulsion of N-hydroxy succinimide or opening of the azlactone.
Although a wide variety of amine-reactive compounds of the type described above, with an amine capturing functional group on one end and a different substrate anchoring functional group on the other end of a divalent linking group, can be conveniently synthesized, many such modifications require difficult separations to achieve the necessary selectively substituted compound. For example, longer or oligomeric divalent linking groups, or, especially, branched or multi-functional linking groups, would be difficult to prepare having a single, substrate specific, reactive functional group on only one end of the molecule. An alternative approach involves converting some or all functional groups to amine capture functional groups. Such molecules could be beneficial for efficient attachment, as well as for control of the activity of the immobilized amine-containing material, especially in biological systems.
Additionally, some surfaces may have few or no complementary functional groups for anchoring amine compounds. Such inert surfaces are often conveniently functionalized by treatment with a surface aminating agent, such as amino alkyl silanes or polyethylene imine. Subsequent exposure of these aminated surfaces to solutions of excess di- or multi-functional amine-capture compounds would convert the surface of the substrate into a surface with grafts of amine-reactive functional groups.
Thus, there exists a need for compounds for reaction with amine-functional surfaces having di- and multi-functional amine-reactive, terminal functional groups.